A known pneumatic device for the transport of loads within tubes comprises a number of tube stages having the cross section either circular, rectangular or square shaped, and are connected end-to-end in any convenient airtight fashion, for instance with sleeve joints, so as to form a single transport tube in which a plurality of rollers are mounted for the containers to run on.
Each of the rollers penetrates through an opening formed in the wall of the tube and projects inwardly beyond the inner surface of the tube. Thus a container, while running inside the tube, will contact only the rollers, without touching the wall. In each tube there are mounted in sets at certain intervals, in cross planes to the tube, three rollers, one at the bottom to support the weight of the containers and two at the sides which function to guide the containers. Each transport tube is provided with a vacuum chamber connected to an exhaust blower through a checkvalve or closure operated so as to be opened either by force accumulators or by electromagnets, or by levers provided with a roller. The electromagnets are controlled by an electromagnetic control block responsive to the presence of the container, while the levers are controlled by contact with the conical front end of the container. The passage of the container from one tube stage to the next is ensured by the opening of the checkvalve downstream of the container.
The device described above has the disadvantage in that the container while running inside the transport tube, may be displaced from the median axis of the transport tube.